[Genetic aspects of valvulopathies]

Valvular dystrophies due to myxoid degeneration are common and potentially serious cardiac pathologies. They constitute a heterogeneous group of which the most usual is idiopathic mitral valvular prolapse (Barlow's disease). The majority of mitral valvular prolapses are sporadic, but there are several familial forms. Transmission is usually autosomal dominant with incomplete penetrance and variable expression. The first chromosomal location to be identified was on the 16p11-13 chromosome. Since then, two other loci have been identified on the 11p15.4 and 13q31-32 chromosomes. Our team has recently identified the first gene responsible for myxoid valvulopathy linked to the X chromosome, from a large family of 318 members. This is the gene that codes for filamin A, which is a cytoskeleton protein. The frequency of mutations in this gene is still unknown, but out of 7 families in which transmission was compatible with X-linked transmission, mutations were discovered in 4 of the families. Thanks to a genetic epidemiological approach, we have also demonstrated that there are familial forms of aortic stenosis, which are probably common. Identification of the genes implicated in these common forms of valvular pathology is important, as it will allow a better understanding of the pathophysiology of these valvular disorders and could lead to better therapeutic management in the future.